Related papers: The dynamics and timescales of static stall
Birds rely on active high-acceleration morphing and flapping to navigate complex airflows, but they can also maintain stable fixed-wing postures under persistent atmospheric disturbances. Here, we show that avian wings exhibit aerodynamic…
In this article, a thorough characterization of the configuration composed by two concentric jets at a low Reynolds number is presented. The analysis comprises a layout with a wide range for the velocity ratio between the inner and outer…
We simulate quasistatic flows of an ideal two-dimensional monodisperse foam around different obstacles, both symmetric and asymmetric, in a channel. We record both pressure and network contributions to the drag and lift forces, and study…
The equations for the sliding of a single block driven by an elastic force show numerically a fast and a slow step in their dynamics when a dimensionless parameter is very large, a limit pertinent for many applications. An asymptotic…
Boats float supported only by buoyancy at rest and at very low speeds. As the speed increases, a hull capable of planing makes a sharp transition to a lifting surface while plowing up the bow wave. As the speed increases further the boat…
Large eddy simulation of a NACA0015 circulation control airfoil using synthetic jets is conducted. A chord Reynolds number of 110000, the excitation frequency of 175 Hz, the momentum coefficients of 0.0044 to 0.0688, and the angles of…
Many experimental and numerical studies report a large reduction of the recirculation bubble in Backward-Facing Step flows or airfoils in stall situation when excited at the natural shedding frequency $f_0$. Through a simple experiment…
Flapping animal flight is often modeled as a combined pitching and heaving motion in order to investigate the unsteady flow structures and resulting forces that could augment the animal's lift and propulsive capabilities. This work isolates…
There is an increasing need to develop a two-dimensional (2D) water entry model including the slamming and transition stages for the 2.5-dimensional (2.5D) method being used on the take-off and water landing of seaplanes, and for the strip…
Self-sustained oscillations arising from the interactions between the hydrodynamic and the acoustic field are disastrous in engineering systems such as segmented solid rocket motors and large gas pipelines. These self-sustained oscillations…
A novel method to estimate unsteady aerodynamic force coefficients from pointwise velocity measurements is presented. The methodology is based on a resolvent-based reduced-order model which requires the mean flow to obtain physical flow…
We study the role of unsteady lift in the context of flapping wings in birds' flight. Both aerodynamicists and biologists attempt to address this subject, yet it seems that the contribution of the unsteady lift still holds many open…
Experiments were conducted in a low-turbulence wind tunnel to investigate the efficacy of localised acoustic forcing upon the dynamics and stability of the flow on a cambered, wall-bounded airfoil over a range of Reynolds numbers (Re) where…
We investigate the effect of imposed kinematics on the self-propulsion of the NACA0015 symmetric airfoil section subject to sinusoidal pitching. We employ a rotary apparatus capable of achieving self-propulsion. A power-spring-based…
The unsteady lift response of an airfoil in a sinusoidal gust can be modeled by two transfer functions: the first-order Sears function and the second-order Atassi function, albeit leading to different results under certain conditions.…
This study investigates active flow control (AFC) of a 30P30N high-lift wing at a Reynolds number Re$_c$ = 450,000 and angle of attack $\alpha$ = 23$^\circ$ using wallresolved large-eddy simulations (LES). Two optimization strategies are…
Present work deals with the dynamics of vehicles which intentionally operate in the ground proximity. The dynamics in ground effect is influenced by the vehicle orientation with respect to the ground, since the aerodynamic force and moment…
The full-field reconstruction of three-dimensional (3D) turbulent flows from sparse experimental measurements remains a significant challenge, particularly for flows exhibiting complex 3D flow separation. In this work, we address this…
This study employs Deep Reinforcement Learning (DRL) for active flow control in a turbulent flow field of high Reynolds numbers at $Re=274000$. That is, an agent is trained to obtain a control strategy that can reduce the drag of a cylinder…
Airfoils pitching in the stalled regime have been of keen interest in recent years due to their desirable aerodynamic force characteristics. In this study, we are numerically investigating the unsteady flow past a NACA 0012 airfoil under…